But who can forbear admiring the nature of the bones? They are very hard; and we see that even the corruption of all the rest of the body, after death, does not affect them. Nevertheless, they are full of numberless holes and cavities that make them lighter; and in the middle they are full of the marrow, or pith, that is to nourish them. They are bored exactly in those places through which the ligaments that knit them are to pass. Moreover, their extremities are bigger than the middle, and form, as it were, two semicircular heads, to make one bone turn more easily with another, that so the whole may fold and bend without trouble. SECT. XXXV. Of the Organs. Within the enclosure of the ribs are placed in order all the great organs such as serve to make a man breathe; such as digest the aliments; and such as make new blood. Respiration, or breathing, is necessary to temper inward heat, occasioned by the boiling of the blood, and by the impetuous course of the spirits. The air is a kind of food that nourishes the animal, and by means of which he renews himself every moment of his life. Nor is digestion less necessary to prepare sensible aliments towards their being changed into blood, which is a liquor apt to penetrate everywhere, and to thicken into flesh in the extreme parts, in order to repair in all the members what they lose continually both by transpiration and the waste of spirits. The lungs are like great covers, which being spongy, easily dilate and contract themselves, and as they incessantly take in and blow out a great deal of air, they form a kind of bellows that are in perpetual motion. The stomach has a dissolvent that causes hunger, and puts man in mind of his want of food. That dissolvent, which stimulates and pricks the stomach, does, by that very uneasiness, prepare for it a very lively pleasure, when its craving is satisfied by the aliments. Then man, with delight, fills his belly with strange matter, which would create horror in him if he could see it as soon as it has entered his stomach, and which even displeases him, when he sees it being already satisfied. The stomach is made in the figure of a bagpipe. There the aliments being dissolved by a quick coction, or digestion, are all confounded, and make up a soft liquor, which afterwards becomes a kind of milk, called chyle; and which being at last brought into the heart, receives there, through the plenty of spirits, the form, vivacity, and colour of blood. But while the purest juice of the aliments passes from the stomach into the pipes destined for the preparation of chyle and blood, the gross particles of the same aliments are separated, just as bran is from flour by a sieve; and they are dejected downwards to ease the body of them, through the most hidden passages, and the most remote from the organs of the senses, lest these be offended at them. Thus the wonders of this machine are so great and numerous, that we find some